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- J Phys Ther Sci
- v.28(11); 2016 Nov
- PMC5140804
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J Phys Ther Sci. 2016 Nov; 28(11): 3078–3083.
Published online 2016 Nov 29. doi:10.1589/jpts.28.3078
PMCID: PMC5140804
PMID: 27942124
Jun Na Zhai, MM,1 Yu Sheng Qiu, PhD,1,* and Jue Wang, PhD1,*
Author information Article notes Copyright and License information PMC Disclaimer
Abstract
[Purpose] This study was to evaluate the effects of orthotics on adults with flexibleflatfoot when wearing orthotic insoles while walking on horizontal ground, walking up anddown stairs and to determine if flexible flatfoot needs treatment. [Subjects and Methods]Fifteen college students with flexible flatfoot and fifteen college students with normalfeet were recruited. First, load rate and contact area were measured by RSscan force platewhen the subjects were walking on horizontal ground, walking up and down 10 cm and 20 cmstairs. Then the subjects with flexible flatfoot were instructed to wear orthotic insolesfor 3 months, and plantar pressure was measured again. Finally, the data were subjected torepeated measures ANOVA. [Results] After treatment for 3 months, the plantar pressure offlatfoot was significantly improved. In addition, the data of the subjects with normalfeet and flatfoot were significantly influenced by walking down 10 cm or 20 cm stairs.[Conclusion] Orthotic insoles could significantly improve the plantar pressure offlatfoot. Additionally, the arches of subjects with normal feet and flatfoot can besignificantly deformed when walking down stairs. Therefore, it is essential for subjectswith flexible flatfoot to wear orthotic insoles to avoid needless injury.
Keywords: Flexible flatfoot, Plantar pressure, Orthotic insoles
INTRODUCTION
Flatfoot, also called pes planus or low arch, refers to a condition in which the mediallongitudinal arch is flat or missing and is one of the common deformities included in lowerlimbs diseases1). Because the alignment ofthe foot is in disorder2), changes in footstructure occur that cause other conditions like ankle arthritis3), pollex valgus4), and foot pain5).
Flatfoot can be divided into rigid flatfoot and flexible flatfoot by its structure6). The arch of the foot in the former case isalways flat when one is in a weight-bearing or non-weight-bearing position, and it willresult in pain or other discomfort7).However, the arch of the foot in the latter case is flat only in a weight-bearing position;in a non-weight-bearing position, the foot arch is the same as in the case of a normalfoot8).
Due to the fact that the arch is always missing in the case of rigid flatfoot, surgicaltreatment is generally needed to correct the structure of the bones9). In contrast, the arch in the case of flexible flatfoot isso plastic that conservative physiotherapy can achieve a corrective effect10). However, sufficient attention has notbeen paid to the conservative treatment of flexible flatfoot. Furthermore, whether flexibleflatfoot needs treatment has always been controversial.
The orthotic insole is a tool used in physiotherapy; however, its effects have not beenclarified. Previous studies have only estimated conservative effects of orthotic on theplantar pressure of individuals with flatfoot on horizontal ground11,12,13), how plantar pressure data vary when walking up and downstairs has not been studied. Therefore, this study measured the data of subjects underdifferent walking conditions to evaluate the effects by wearing orthotic insoles and furtherdetermine if conservative treatment is needed.
SUBJECTS AND METHODS
This study was approved by the Ethics Committee of the First Affiliated Hospital of Xi’anJiaotong University, and informed consent was provided by the subjects.
Fifteen adults with flexible flatfoot and fifteen adults with normal feet were recruitedafter determining their status by collecting their foot prints using an RSscan force plate.All subjects were college students who had not had any lower limb diseases in the past 6months. There was no significant difference in age, height, weight, or foot length betweensubjects with flexible flatfoot and subjects with normal feet. For the subjects withflatfoot, the arch was missing in a load-bearing position, the proportion of the midfootprint between the hollow area and solid area was 1/2, or the hollow area was missing. Forthe subjects with normal feet, the arch was always present, and the proportion was 2/1.
This study used an RSscan force plate (RS footscan USB 7), which has an area of 40 × 50 cmand 4,096 sensors; this device can measure dynamic plantar pressure. The foot wasautomaticlly divided into 10 parts by the plate, including toe 1, toes 2–5, the firstmetatarsal bone, the second metatarsal bone, the third metatarsal bone, the forth metatarsalbone, the fifth metatarsal bone, the mid foot, the medial heel, and the lateral heel. Due tothe arch of the midfoot being the main difference between a flatfoot and normal foot14), this study focused on only the load rateand contact area of the midfoot.
After performing walking exercise several times, the subjects were asked to walk onhorizontal ground and to walk up or down 10 cm or 20 cm stairs at one step per second insocks (the same socks for each subject) while not wearing shoes. Under each walkingcondition, the RSscan force plate was used to record data for load rate and contact area.Each variable was measured 3 times, and the mean value was calculated. Then the subjectswith flexible flatfoot were asked to wear shoes (the same shoes for each subject) containingthe orthotic insoles 8 hours per day for 3 months, and plantar pressure was measured againafter treatment. Once recording of data was complete, the data were divided into thefollowing 3 groups: flatfoot before treatment, flatfoot after treatment, and normal feet.Each group was further divided according to 5 walking conditions: walking on horizontalground, walking up 10 cm stairs, walking up 20 cm stairs, walking down 10 cm stairs, andwalking down 20 cm stairs. Repeated measures ANOVA was performed using spss 13.0, and thelevel of significance was set at p<0.05. The 95% confidence interval (CI) (p<0.05) wasconsidered statistically significant. The 5 walking conditions were consideredwithin-subjects variables, and the 3 groups were considered between-subjects factors.
This study measured the dynamic load rate and contact area by RSscan force plate insubjects walking under different conditions. The load rate (in N/ms) can be used to indicatethe load-bearing ratio for various regions of the foot per millisecond15). The contact area can be used to indicate the area ofcontact between various regions of the foot and the ground, and it is shown in squarecentimeters16). The values for both ofthese variables are larger in the midfoot in individuals with flatfoot compared with thosewith normal feet17). Because the arch ofthe foot is decreased in individuals with flatfoot in a weight-bearing position, thestructure of the bones of the foot is further deformed, which makes both the contact areaand load rate of the midfoot larger.
The orthotic insoles in this study were made of an EVA resin material that was a copolymerof ethylene and vinyl acetate. The thickness of foot arch was 2.6 cm, and the thickness offore foot and heel was 0.4 cm.
RESULTS
After treatment, load rate and contact area were significantly improved in subjects withflexible flatfoot. In addition, there were significant differences in load rate and contactarea between before and after treatment (p<0.01). However, the posttreatment data werestill significantly different from those of subjects with normal feet (p<0.01) (Tables 1 and and2Table2).
Table 1.
Load rates for the 3 groups
| Group | Group | Mean difference | Std. error | 95% confidence interval for difference(2) | ||
|---|---|---|---|---|---|---|
| Lower bound | Upper bound | |||||
| Left foot | Before | Before | ||||
| After | 0.50* | 0.17 | 0.17 | 0.84 | ||
| Normal | 1.18* | 0.17 | 0.84 | 1.51 | ||
| After | Before | −0.50* | 0.17 | −0.84 | −0.17 | |
| After | ||||||
| Normal | 0.68* | 0.17 | 0.34 | 1.01 | ||
| Normal | Before | −1.18* | 0.17 | −1.51 | −0.84 | |
| After | −0.68* | 0.17 | −1.01 | −0.34 | ||
| Normal | ||||||
| Right foot | Before | Before | ||||
| After | 0.67* | 0.16 | 0.35 | 0.99 | ||
| Normal | 1.09* | 0.16 | 0.77 | 1.41 | ||
| After | Before | −0.67* | 0.16 | −0.99 | −0.35 | |
| After | ||||||
| Normal | 0.42* | 0.16 | 0.10 | 0.74 | ||
| Normal | Before | −1.09* | 0.16 | −1.41 | −0.77 | |
| After | −0.42* | 0.16 | −0.74 | −0.10 | ||
| Normal | ||||||
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Based on estimated marginal means. *The mean difference is significant at the 0.05level. Before: flatfoot before treatment; After: flatfoot after treatment; Normal:normal feet
Table 2.
Contact areas for the 3 groups
| Group | Group | Mean difference | Std. error | 95% confidence interval for difference(2) | ||
|---|---|---|---|---|---|---|
| Lower bound | Upper bound | |||||
| Left foot | Before | Before | ||||
| After | 10.65(*) | 0.86 | 8.90 | 12.39 | ||
| Normal | 12.60(*) | 0.86 | 10.85 | 14.34 | ||
| After | Before | −10.65(*) | 0.86 | −12.39 | −8.90 | |
| After | ||||||
| Normal | 1.95(*) | 0.86 | 0.20 | 3.69 | ||
| Normal | Before | −12.60(*) | 0.86 | −14.34 | −10.85 | |
| After | −1.95(*) | 0.86 | −3.69 | −0.20 | ||
| Normal | ||||||
| Right foot | Before | Before | ||||
| After | 8.16(*) | 0.49 | 7.16 | 9.15 | ||
| Normal | 9.93(*) | 0.49 | 8.93 | 10.92 | ||
| After | Before | −8.16(*) | 0.49 | −9.15 | −7.16 | |
| After | ||||||
| Normal | 1.77(*) | 0.49 | 0.77 | 2.77 | ||
| Normal | Before | −9.93(*) | 0.49 | −10.92 | −8.93 | |
| After | −1.77(*) | 0.49 | −2.77 | −0.77 | ||
| Normal | ||||||
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Based on estimated marginal means. *The mean difference is significant at the 0.05level. Before: flatfoot before treatment; After: flatfoot after treatment; Normal:normal feet
Additionally, there was no intersection of 95% CIs between before and after treatment underany of the walking conditions. However, the 95% CIs for the subjects with flatfoot aftertreatment and those with normal feet did intersect under the conditions of walking down10 cm and 20 cm stairs (Tables 3 and and4Table4).
Table 3.
Load rates for the 5 walking conditions
| Group | Conditions | Mean difference | Std. error | 95% confidence interval for difference (2) | ||
|---|---|---|---|---|---|---|
| Lower bound | Upper bound | |||||
| Left foot | Before | Ground | 1.7 | 0.1 | 1.6 | 1.9 |
| Up 10 cm stairs | 1.7 | 0.1 | 1.5 | 1.8 | ||
| Up 20 cm stairs | 1.6 | 0.1 | 1.5 | 1.7 | ||
| Down 10 cm stairs | 3.4 | 0.2 | 3.0 | 3.8 | ||
| Down 20 cm stairs | 5.2 | 0.3 | 4.6 | 5.8 | ||
| After | Ground | 1.4 | 0.1 | 1.3 | 1.5 | |
| Up 10 cm stairs | 1.3 | 0.1 | 1.2 | 1.5 | ||
| Up 20 cm stairs | 1.3 | 0.1 | 1.2 | 1.4 | ||
| Down 10 cm stairs | 2.3 | 0.2 | 2.0 | 2.7 | ||
| Down 20 cm stairs | 3.5 | 0.3 | 2.9 | 4.1 | ||
| Normal | Ground | 0.9 | 0.1 | 0.7 | 1.0 | |
| Up 10 cm stairs | 0.7 | 0.1 | 0.6 | 0.9 | ||
| Up 20 cm stairs | 0.6 | 0.1 | 0.5 | 0.7 | ||
| Down 10 cm stairs | 1.8 | 0.2 | 1.4 | 2.2 | ||
| Down 20 cm stairs | 3.7 | 0.3 | 3.1 | 4.3 | ||
| Right foot | Before | Ground | 1.6 | 0.1 | 1.5 | 1.7 |
| Up 10 cm stairs | 1.5 | 0.1 | 1.4 | 1.6 | ||
| Up 20 cm stairs | 1.5 | 0.1 | 1.4 | 1.6 | ||
| Down 10 cm stairs | 3.1 | 0.2 | 2.8 | 3.5 | ||
| Down 20 cm stairs | 4.8 | 0.3 | 4.1 | 5.4 | ||
| After | Ground | 1.2 | 0.1 | 1.1 | 1.4 | |
| Up 10 cm stairs | 1.2 | 0.1 | 1.1 | 1.3 | ||
| Up 20 cm stairs | 1.2 | 0.1 | 1.0 | 1.3 | ||
| Down 10 cm stairs | 2.2 | 0.2 | 1.9 | 2.6 | ||
| Down 20 cm stairs | 3.3 | 0.3 | 2.7 | 3.9 | ||
| Normal | Ground | 0.8 | 0.1 | 0.7 | 0.9 | |
| Up 10 cm stairs | 0.7 | 0.1 | 0.6 | 0.8 | ||
| Up 20 cm stairs | 0.6 | 0.1 | 0.5 | 0.7 | ||
| Down 10 cm stairs | 1.8 | 0.2 | 1.5 | 2.2 | ||
| Down 20 cm stairs | 3.1 | 0.3 | 2.5 | 3.7 | ||
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Before: flatfoot before treatment; After: flatfoot after treatment; Normal: normalfeet
Table 4.
Contact areas for the 5 walking conditions
| Group | Conditions | Mean difference | Std. error | 95% confidence interval for difference (2) | ||
|---|---|---|---|---|---|---|
| Lower bound | Upper bound | |||||
| Left foot | Before | Ground | 52.4 | 0.5 | 51.4 | 53.5 |
| Up 10 cm stairs | 52.1 | 0.5 | 51.0 | 53.1 | ||
| Up 20 cm stairs | 51.7 | 0.5 | 50.7 | 52.7 | ||
| Down 10 cm stairs | 55.2 | 0.7 | 53.8 | 56.7 | ||
| Down 20 cm stairs | 58.6 | 1.0 | 56.6 | 60.5 | ||
| After | Ground | 42.0 | 0.5 | 40.9 | 43.1 | |
| Up 10 cm stairs | 41.8 | 0.5 | 40.7 | 42.9 | ||
| Up 20 cm stairs | 41.8 | 0.5 | 40.8 | 42.8 | ||
| Down 10 cm stairs | 44.8 | 0.7 | 43.4 | 46.3 | ||
| Down 20 cm stairs | 46.3 | 1.0 | 44.3 | 48.2 | ||
| Normal | Ground | 39.3 | 0.5 | 38.2 | 40.3 | |
| Up 10 cm stairs | 38.7 | 0.5 | 37.6 | 39.8 | ||
| Up 20 cm stairs | 38.3 | 0.5 | 37.3 | 39.3 | ||
| Down 10 cm stairs | 43.3 | 0.7 | 41.8 | 44.7 | ||
| Down 20 cm stairs | 47.4 | 1.0 | 45.5 | 49.4 | ||
| Right foot | Before | Ground | 50.2 | 0.4 | 49.4 | 51.0 |
| Up 10 cm stairs | 50.1 | 0.4 | 49.3 | 50.9 | ||
| Up 20 cm stairs | 50.0 | 0.4 | 49.1 | 50.7 | ||
| Down 10 cm stairs | 53.0 | 0.4 | 52.3 | 53.7 | ||
| Down 20 cm stairs | 55.8 | 0.4 | 54.9 | 56.6 | ||
| After | Ground | 42.2 | 0.4 | 41.4 | 42.9 | |
| Up 10 cm stairs | 41.8 | 0.4 | 41.0 | 42.6 | ||
| Up 20 cm stairs | 41.8 | 0.4 | 41.1 | 42.6 | ||
| Down 10 cm stairs | 45.0 | 0.4 | 44.3 | 45.8 | ||
| Down 20 cm stairs | 47.4 | 0.4 | 46.6 | 48.2 | ||
| Normal | Ground | 40.1 | 0.4 | 39.3 | 40.9 | |
| Up 10 cm stairs | 39.6 | 0.4 | 38.8 | 40.4 | ||
| Up 20 cm stairs | 39.4 | 0.4 | 38.6 | 40.2 | ||
| Down 10 cm stairs | 44.0 | 0.4 | 43.3 | 44.7 | ||
| Down 20 cm stairs | 46.3 | 0.4 | 45.4 | 47.1 | ||
Open in a separate window
Before: flatfoot before treatment; After: flatfoot after treatment; Normal: normalfeet
All the results indicated that although there was still a difference between subjects withflatfoot after treatment and those with normal feet, the data for load rate and contact areawere significantly corrected under the different conditions, especially when walking downstairs. In other words, the data of the subjects with flatfoot changed after treatment,becoming more similar to the data of the subjects with normal feet.
Furthermore, the 95% CIs for walking down stairs did not intersect with those for any otherwalking conditions (Tables 3 andand 4). 4). This showed that the arches of the subjectswith normal feet, in addition to those with flexible flatfoot, were deformed when walkingdown 10 cm stairs or 20 cm stairs.
DISCUSSION
The present study showed that the load rate and contact area of the subjects with flexibleflatfoot were larger than those of the subjects with normal feet, which was consistent withprevious studies18,19,20). However, the datarevealed that these variables were corrected effectively after 3 months of treatmentconsisting of wearing orthotic insoles. The results could be explained by the orthoticinsoles increasing the arch height of the foot and correcting the alignment of foot bones,which could further improve plantar pressure21). With the increase in the height of foot arch, the weight-bearingsites were changed from the midfoot to the fore foot and heel. Therefore, the contact areaand load rate of the midfoot were decreased. However, due to the limited time of orthotictreatment, there was still a significant difference between the subjects with flatfoot aftertreatment and those with normal feet.
Previous studies only focused on the effects of orthotics on plantar pressure on horizontalground18,19,20). None had estimated theeffects of orthotics on plantar pressure while walking up and down stairs. In this study, itwas observed that orthotic insoles could correct the plantar pressure of subjects withflatfoot not only on horizontal ground, but also when walking up and down stairs. This maybecause the orthotics were able to correct the abnormal structure of the foot22), suppress the eversion of thetalocalcaneal joint23), and furtherimprove the joint angles of the lower limbs while walking up and down stairs.
It should be noted, however, that the highest values for load rate and contact area werefor walking down 20 cm stairs and that the second highest values were for walking down 10 cmstairs. This may be due to the fact that when someone is going down stairs, the plantarpressure of the midfoot is affected not only by the body weight but is also affected by theacceleration of gravity, which causes greater loading of the midfoot24). Therefore, when walking down stairs, the plantar pressurebecame larger with the increase in stair height.
It should also be noted that the values for load rate and contact area when walking downstairs were significantly larger than when walking on horizontal ground or up stairs in bothgroups of subjects. This shows that when walking down stairs, the arch of the foot isdeformed badly not only in subjects with flatfoot but also in those with normal feet. Inindividuals with normal feet, the arch of the foot needs a certain amount of elasticity toprotect plantar vessels and nerves from compression25); however, the arch can be influenced by the impact of the foot withthe stairs when walking down stairs. In individuals with flatfoot, the stability of the archis so weak that it is more easily deformed when walking down stairs. That is to say, walkingdown stairs is harmful to the arch of the foot. This is important because people generallychoose to take an elevator when traveling to higher floors in a building, but when travelingto lower floors, they generally prefer to take the stairs rather than wait for an elevator,as long as the number of floors is not too high.
Finally, insufficient attention has been paid to the conservative treatment of flexibleflatfoot, and whether adults with flexible flatfoot need to be treated has always beencontroversial2, 10). The present study shows that flatfeet and even normal feet areinfluenced by walking down stairs. Furthermore, none of the participants experienceddiscomfort during the treatment, and the therapeutic effects were apparent. Therefore, useof orthotic insoles could be recommended for treatment of flexible flatfoot to preventfurther development. However, further study should be conducted to estimate the effects oforthotics on other plantar pressure variables in the future.
Conflict of interest
The authors declare that there have no conflicts of interest.
Acknowledgments
This study was supported by funds provied by the Orthopedic Department of the FirstAffiliated Hospital of Xi’an Jiaotong University.
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